Copolymerization Approach to Improving Ru(II)-Complex/C3N4 Hybrid Photocatalysts for Visible-Light CO2 Reduction

Constantine Tsounis, Ryo Kuriki, Kengo Shibata, Junie Jhon M. Vequizo, Daling Lu, Akira Yamakata, Osamu Ishitani, Rose Amal, Kazuhiko Maeda

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


Copolymerized carbon nitride nanosheets (NS-C3N4) were used as a light absorbing unit while paired with a Ru(II) complex that served as a catalyst for CO2 reduction, forming a hybrid photocatalytic system. Copolymerization with urea and phenylurea in air at 823 K resulted in a carbon nitride material that had wide visible light absorption extending to 650 nm, significantly red-shifted compared to the absorption edge of pristine NS-C3N4, an analogue prepared with only urea (ca. 435 nm). While a hybrid system consisting of pristine NS-C3N4 was found to be inactive under longer wavelength visible light (λ > 500 nm) due to its large band gap, the copolymerized material was able to catalytically convert CO2 to HCOOH under λ > 500 nm irradiation. Furthermore, its activity toward HCOOH production is doubled under λ > 400 nm irradiation after 5 h compared to pristine NS-C3N4. Transient absorption spectroscopy clearly showed improved lifetime of photogenerated free (and/or shallowly trapped) electrons, which should be the key to enhancing the photocatalytic activity of this hybrid system even under shorter wavelength visible light.

Original languageEnglish
Pages (from-to)15333-15340
Number of pages8
JournalACS Sustainable Chemistry and Engineering
Issue number11
Publication statusPublished - Nov 5 2018
Externally publishedYes


  • Artificial photosynthesis
  • Carbon nitride
  • Heterogeneous photocatalysis
  • Hybrid photocatalyst
  • Solar fuels

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry
  • Chemical Engineering(all)
  • Renewable Energy, Sustainability and the Environment


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